case PUT: {
Object val = t.pop();
Object key = t.pop();
- ((JS)t.peek()).put(key, val);
+ JS target = (JS)t.peek();
+ if (target == null) throw new JS.Exn("tried to put a value to the " + key + " property on the null value");
+ target.put(key, val);
t.push(val);
break;
}